Modelling of the bedrock channels of the Mekong River

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Abstract

Additional master thesis - To mitigate the effects of the hydropower dam development on the Mekong river system, research must be done on the effects of sediment catchment of these dams. With unknown amounts of sediment, stored in the banks and in local bars, all spread over this long bedrock channel, local sediment transports are hard to predict. Especially, in the case of implementation of a dam, the reduction in available sediment and so the sediment transport is difficult to determine. In this research different Delft3D input is tested to model the reduction in sediment transport. The various options were the local change of roughness, change of threshold for sediment reduction for sediment close to non-erodible layers, increasing the density (locally) of sediment, controlling the maximum erosion as percentage of the water depth and the local change of available sediment at the bed. This was all done using two different sediment transport formulations of Wilcock, both for sand-gravel mixtures. The best solution turned out to be the change of the threshold for sediment reduction for sediment close to non-erodible layers. However, disadvantage here, was the inability to change this parameter locally, to be able to determine where sediment buffers in the model are located.